Sound-transmitting apparatus.



' .Witnes'ses H. W. ROGERS.

SOUND TRANSMITTING APPARATUS.

APPTICATION FILED APR. 19. 1916.

l m msn mm Jan 115 1918,

2 SHEETS SHEET l- 721mm v y x H.'W. ROGERS. SOUND TRANSMITTING APPARATU. AVPPLICATION FILED APR. 19. I916.

Patented Jan. 15,1918.

'2 SHEETSSHEET 2.

Attorneys 7, whereby sounds are produced corresponding to the vibrations of the bar 9. Instead "of the bar 9 being a needle bar, and having assembling them in a convenient manner, by

means of straps 1 1, or in any other convenient manner. This will rigidly connect the permanent magnet and sound box to hold them in proper relative position. The bar 9, which provides'an armature lever, is pivotally. connected between its ends to one ter- "minal of the magnet-13 preferably to that limb ofthe magnet to which the sound box is attached. The armature lever'9 can be readily fulcrumed to the terminal of the electromagnet by means of a link 15 or any other suitable manner.

The other limb of the magnet 13 is shorter than the first mentioned limb whichis attached to the sound box, to accommodate A an electromagnet 16 adjacent the terminal thereof, and which has its core 17 elongated and in fact constituting one pole of the permanent magnet. One arm of the armature lever 9 projects close adjacent theend.

of the core 17 to provide an air gap 18 between said core and armature lever which can'be adjusted, as will presently appear.

a The core 17 of the electromagnet'extends rearwardly therefrom and is slidable within a bore 19 extending longitudinally through the respective limb of the magnet 13, whereby saidcore can he slid to carry the electromagnet longitudinally.therewith, whereby to adjust the air gap 18. As a convenient means for adjusting the core 17,

the rear. terminal thereof has rotatably. mounted thereon a tubular adjusting screw 20 threaded into the basal portion of the re spective limb of the magnet 13. The core 17 is made to move longitudinally with the screw 20, this being readily accomplished by providing the core 17 with an annular groove 21 receiving a pin 22 engaged within the screw 20. Any other suitable means,

however. can be provided for adjusting the core. With the present device, when the screw 20 is rotated, the core is adjusted longitudinally to move it either toward or away from the armature lever, whereby an accurate adjustment of the air gap is possible. The permanent magnet 13,. together with the. core 1'1 and respective arm of the armature lever 9 provide a magnetic circuit, and

ture lever 9, to prevent the armature lever from sticking to the core, whereby to enhance the responsiveness of the armature lever to slight variations in the current traversing the electromagnet.

The-electromagnet 16 is interposed in an electrical circuit 23,- which includes .a battery24 or any other suitable source of electrical energy, a switch 2 5, and a microphone or equivalent .transmitting device 26. As illustrated inFig. 2, this microphone26 is provided with a needle 27 for operating it, and adapted to engage the phonic groove of a sound producing record 28, although it is to be understood that the microphone can be operated by sound waves direct, to control the current flowing through the microphone and electromagnet. The microphone can be disposed at'any suitable distance from the sound box, and a number of electromagnets 16 can be connected in the circuit, whereby a plurality of sound producing apparatus 7 can be used with a single microphone .or transmitter. V

The limbs of the permanent magnet 13 can be held spaced and rigid by means of a spacer 29 therebetween, and said magnet and sound box can be supported in any suitable manner at the desired point where the sounds are to be produced in a theater, hall,

sound waves, and the electromagnet in be 1 'ing energized will counteract the magnetism of the permanent magnet. In other words, the magnetism created by the electromagnet opposes or counteracts the magnetism of the core 17, thereby resulting in the movement of the armature lever, and as the impulses change in rapid succession, the armature lever will .be vibrated, to correspond with the sound waves, thus controlling the valve 7 correspondingly, and resulting in the produ ction of the sound waves by the diaphragm 4 passing out through the tube or horn 3.

The sound box serves to greatly amplify the sound waves, whereby there is a mate rially increased volume of sound, retaining the fine. qualities thereof.

The advantages and attributes of the pres,-

31,253,53d I ma permanent magnet, an armature controlling said valve, and an electromagnet having a core adjustably carried by the permanent magnet and forming a part of the magnetic circuit, there being an air gap between said core and armature WlllCl'LCilIl be controlled by the adjustment of the core, and the armature being responsive to the electromagnet. 2. The combination with a pneumatic sound box and its controlling valve, of a permanent U-shaped magnet having one" .limb shorter than the other, an armature lever fulcrumed between its ends to the ter minal of the second mentioned limb, one arm of said lever controlling said valve, an electromagnet having an elongated core 'slidably engaging the first mentioned limb ,of the magnet and cooperating With the other arm of the armature lever, the first mentioned limb of the magnet accommodating the electromagnet, the permanent magnet together With the core and second mentioned arm of the armature lever providing a magnetic circuit, there being an air gapbetvveen the core and. armature lever which can be adjusted by adjusting the core.

3. The combination with a pneumatic sound box and its controlling valve, of electro-magnetic means for controlling said valve, including a permanent magnet, an

adjustable core mounted in said magnet, a coil surrounding said core, and an armature lever operably connected to the valve at one end and disposed in attractive relation the core, said core being adjustable to regir late the air gap betiveen it and thearmature. I a. The combination with a pneumatic sound boX and its controlling valve, oi? electro-magnetic means for controlling said valve, including an electro-magnet having a hollow core, said ele'ctro-magnet being double poled, one of said poles being provided with a longitudinal bore therethrough, a coil surroundingsaid core, and an arma ture fulcrumed intermediate of its ends, one

of said ends being operably connected to the valve and-the other being disposed in attractive relation to thepole.

5. The combination with a pneumatic sound boX and its controlling valve, of electro-magnetic means for controlling said valve,-including a double poled electro-magnet, one of said poles being provided with a longitudinal bore therethrough, a core mounted in said bore for longitudinal movement, adjusting means connected to the core and to the magnet foriimparting longitudinal movement to the core, a coil surrounding one end of the core, and an armature fulcrumed intermediate of its ends and havmg one end operably connected to the valve and the other disposed in attractive relation to the core.

Tn testimony that T claim the foregoing as my own, I have hereto affixed my signature.

HARRISON W. ROGERS. 

